added in basic process for sloping ceiling

backend/app/plan/schemas.py

@@ -9,7 +9,9 @@ TYPICAL_MEASURE_TYPES = [
 ]
 
 WALL_INSULATION_MEASURES = ["internal_wall_insulation", "external_wall_insulation", "cavity_wall_insulation"]
-ROOF_INSULATION_MEASURES = ["loft_insulation", "flat_roof_insulation", "room_roof_insulation"]
+ROOF_INSULATION_MEASURES = [
+    "loft_insulation", "flat_roof_insulation", "room_roof_insulation", "sloping_ceiling_insulation"
+]
 
 # Both all and roof insulaiton measures are eligible for ECO4. These are the remaining fabric and heating measures
 # This is based on th measures we have recommendations for
@@ -31,7 +33,7 @@ SPECIFIC_MEASURES = (
 
 INSULATION_MEASURES = [
     "internal_wall_insulation", "external_wall_insulation", "cavity_wall_insulation",
-    "loft_insulation", "flat_roof_insulation", "room_roof_insulation",
+    "loft_insulation", "flat_roof_insulation", "room_roof_insulation", "sloping_ceiling_insulation",
     "suspended_floor_insulation", "solid_floor_insulation",
 ]
 
@@ -46,7 +48,9 @@ MEASURE_MAP = {
     "wall_insulation": [
         "internal_wall_insulation", "external_wall_insulation", "cavity_wall_insulation",
     ],
-    "roof_insulation": ["loft_insulation", "flat_roof_insulation", "room_roof_insulation"],
+    "roof_insulation": [
+        "loft_insulation", "flat_roof_insulation", "room_roof_insulation", "sloping_ceiling_insulation"
+    ],
     "floor_insulation": ["suspended_floor_insulation", "solid_floor_insulation"],
     "heating": ["boiler_upgrade", "high_heat_retention_storage_heaters", "air_source_heat_pump"],
     "windows": ["double_glazing", "secondary_glazing"],

recommendations/Costs.py

@@ -1,4 +1,6 @@
+from typing import Mapping, Any
 import numpy as np
+
 from recommendations.county_to_region import county_to_region_map
 from utils.logger import setup_logger
 from backend.ml_models.AnnualBillSavings import AnnualBillSavings
@@ -166,7 +168,8 @@ class Costs:
         "room_roof_insulation": 0.26,
         "heater_removal": 0.1,
         "sealing_open_fireplace": 0.1,
-        "mechanical_ventilation": 0.26
+        "mechanical_ventilation": 0.26,
+        "sloping_ceiling_insulation": 0.26  # Similar to IWI so using the same contingency
     }
 
     # Preliminaries are a percentage of the total cost of the work and covers the cost of site-specific costs
@@ -935,3 +938,66 @@ class Costs:
             "labour_hours": 80,
             "labour_days": 10,
         }
+
+    @staticmethod
+    def _estimate_number_of_days_for_sloping_ceiling(insulation_roof_area: float) -> float:
+        """
+        Estimate labour days required to insulate an existing sloping ceiling.
+
+        Heuristic model based on retrofit guidance (Checkatrade, The Green Age)
+        and analogy with internal wall insulation.
+
+        Assumptions:
+        - ~30 m² of sloping ceiling takes ~4 working days
+        - Small jobs still require multiple days (setup, stripping, reboarding)
+        - Larger areas benefit from economies of scale, but not linearly
+
+        :param insulation_roof_area: m² of sloping ceiling to be insulated
+        """
+
+        base_days = 4
+        base_area = 30  # m2 reference case
+        labour_exponent = 0.85
+        min_days = 2
+
+        labour_days = max(
+            min_days,
+            base_days * (insulation_roof_area / base_area) ** labour_exponent
+        )
+
+        return labour_days
+
+    @classmethod
+    def sloping_ceiling_insulation(cls, insulation_roof_area: float) -> Mapping[str, Any]:
+        """
+        This costing for this is based on Checkatrade desktop research, since we are yet to receive installer quotes.
+        :param insulation_roof_area: Area of the sloping ceiling to be insulated
+        :return:
+        """
+        ################
+        # Assumptions
+        ################
+        # Sources:
+        # https://www.checkatrade.com/blog/cost-guides/vaulted-ceiling-cost/
+        # https://www.thegreenage.co.uk/can-i-insulate-my-sloping-ceiling/
+        # These assumptions last updated 21/02/2026
+        insulation_cost_per_m2 = 52  # The actual install process is quite similar to IWI
+        labour_rate = 250  # per day
+        contingency_rate = cls.CONTINGENCIES["sloping_ceiling_insulation"]
+
+        labour_days = cls._estimate_number_of_days_for_sloping_ceiling(insulation_roof_area)
+        labour_hours = labour_days * 8
+
+        total = (insulation_cost_per_m2 * insulation_roof_area) + (labour_rate * labour_days)
+
+        # Assume VAT included in the total => total is 120% of subtotal
+        vat = total - (total / 1.2)
+
+        return {
+            "total": total,
+            "contingency": total * contingency_rate,
+            "contingency_rate": contingency_rate,
+            "vat": vat,
+            "labour_hours": labour_hours,
+            "labour_days": labour_days,
+        }

recommendations/RoofRecommendations.py

@@ -324,10 +324,11 @@ class RoofRecommendations:
         )
 
         self.estimated_u_value = u_value
+        # The Roof is already compliant - in this case, the u-value is beyond the requirements for
+        # Building Regs Part L and so we don't recommend anything
         if (u_value <= self.BUILDING_REGULATIONS_PART_L_MAX_U_VALUE) or all(
             m not in measures for m in MEASURE_MAP["roof_insulation"]
         ):
-            # The Roof is already compliant
             return
 
         non_invasive_recommendations = self.property.non_invasive_recommendations
@@ -381,14 +382,12 @@ class RoofRecommendations:
             has_room_roof_recommendation=has_room_roof_recommendation
         )
 
-        ##################################################
+        ################################################################
         # ~~~~~ Loft Insulation Recommendation Logic ~~~~~
-        ##################################################
+        ################################################################
-        # We firstly handle non-intrusive recommendations, which may override the normal roof insulation recommendations
         if needs_loft_insulation:
             self.recommend_roof_insulation(
                 u_value=u_value,
-                insulation_thickness=self.insulation_thickness,
                 phase=phase,
                 is_flat=False,
                 is_pitched=True,
@@ -396,10 +395,12 @@ class RoofRecommendations:
             )
             return
 
+        ################################################################
+        # ~~~~~ Flat Roof Insulation Recommendation Logic ~~~~~
+        ################################################################
         if needs_flat_roof_insulation:
             self.recommend_roof_insulation(
                 u_value=u_value,
-                insulation_thickness=0,
                 phase=phase,
                 is_flat=True,
                 is_pitched=False,
@@ -407,12 +408,21 @@ class RoofRecommendations:
             )
             return
 
+        ################################################################
+        # ~~~~~ Room Roof Insulation Recommendation Logic ~~~~~
+        ################################################################
         # There are cases where the property might have a room roof as the second roof, but we have a recommendation for
         # it, so we allow this override
         if needs_rir_insulation:
             self.recommend_room_roof_insulation(u_value, phase, default_u_values)
             return
 
+        ####################################################################################################
+        # ~~~~~ Sloping Ceiling Insulation Recommendation Logic ~~~~~
+        ####################################################################################################
+        if needs_sloping_ceiling:
+            self.recommend_sloping_ceiling()
+
         raise NotImplementedError("Implement me")
 
     @staticmethod
@@ -432,7 +442,7 @@ class RoofRecommendations:
         raise ValueError("Invalid material type")
 
     def recommend_roof_insulation(
-        self, u_value, insulation_thickness, phase, is_pitched, is_flat, default_u_values
+        self, u_value, phase, is_pitched, is_flat, default_u_values
     ):
 
         """
@@ -773,3 +783,55 @@ class RoofRecommendations:
                 )
 
         self.recommendations = recommendations
+
+    def recommend_sloping_ceiling(self, phase: int, u_value, sloping_ceiling_recommendation: dict = None):
+        """
+        Recommend insulation for a sloping ceiling
+        Since we don't have any materials from installers for this specific recommendation, we
+        do not iterate through any materials. Instead, we provide a single recommendation, we estimated
+        prices based on desk research.
+        :return:
+        """
+
+        new_description = "Pitched, insulated"
+        new_efficiency = "Good"
+
+        roof_ending_config = RoofAttributes(new_description).process()
+        roof_simulation_config = check_simulation_difference(
+            new_config=roof_ending_config, old_config=self.property.roof, prefix="roof_"
+        )
+
+        # We pull out new u-values, based on 75mm of insulation, with u-values defined from Elmhurst
+        new_u_value = 0.5  # This doesn't change, regardless of starting u-value
+
+        simulation_config = {
+            **roof_simulation_config,
+            "roof_thermal_transmittance_ending": new_u_value,
+            "roof_energy_eff_ending": new_efficiency
+        }
+
+        cost_result = self.costs.sloping_ceiling_insulation(
+            roof_area=self.property.roof_area  # For a pitched roof, this is the pitched roof area
+        )
+
+        self.recommendations = [
+            {
+                "phase": phase,
+                "parts": [],
+                "type": "sloping_ceiling_insulation",
+                "measure_type": "sloping_ceiling_insulation",
+                "description": "Insulate sloping ceilings at the rafters and re-decorate",
+                "starting_u_value": u_value,
+                "new_u_value": None,
+                "sap_points": sloping_ceiling_recommendation.get("sap_points", None),
+                "simulation_config": simulation_config,
+                "description_simulation": {
+                    "roof-description": new_description,
+                    "roof-energy-eff": new_efficiency
+                },
+                **cost_result,
+                "already_installed": "sloping_ceiling_insulation" in self.property.already_installed,
+                "survey": sloping_ceiling_recommendation.get("survey", None),
+                "innovation_rate": 0
+            }
+        ]